The overall purpose of the Biostatistics Core is to provide support in the areas of research design, data entry and management, statistical analysis, and presentation of results for projects and research in the Mid-American Adolescent Sexually Transmitted Disease Clinical Research Center. In addition, the Core will seek to develop new statistical methodology as the need arises. In addition to managing data collected specifically for these projects, the Core will also abstract and merge data required from the Bell Flower Sexually Transmitted Diseases Clinic database, the IU Chlamydia Laboratory database, the Marion Country Health Department Laboratory database and the Regenstrief Medical Records System. The existence of the Core also assures that any unforeseen statistical analyses or design problems will immediately be brought to the attention of professionals with expertise in these areas. Details on the specific methodologies and statistical analyses for each project appear in the individual proposals.